1. Field of the Invention
The presents invention relates to an apparatus for decomposing perfluorinated compounds and to a system for processing perfluorinated compounds.
A claim of priority is made to Korean Patent Application No. 2002-23508, filed in the Korean Intellectual Property Office on Apr. 29, 2002, the entirety of which is incorporated herein in by reference.
2. Description of the Related Art
Perfluorinated compounds (PFCs) are toxic waste gases generated and exhausted into the air during the manufacture of semiconductor devices. PFCs are commonly used in dry etching, chemical vapor deposition, and chamber cleaning processes. Typical examples of PFCs include CF4, C2F6, C3F8, CHF3, NF3, SF6, and the like. PFCs are very stable compounds inherently having a strong binding force, so they are resistant to decomposition and have a long lifespan. Furthermore, the global warming potential of PFCs is much higher than that of carbon oxide, which has prompted the World Semiconductor Council to voluntarily take steps to reduce the discharge of the PFCs.
A conventional technique for processing PFCs exhausted during the manufacture of semiconductor devices is disclosed in U.S. Statutory Invention Registration (SIR) No. H1701. According to this method, fluorine in the exhaust gas is reacted with aluminum to produce AlF3 as a waste form. However, the addition of aluminum increases costs. In addition, the requirement for additional equipment for processing the reaction product increases the overall processing system size and maintenance and management functions.
There exist a variety of PFC processing methods, including a method involving the addition of alkaline earth metals and a powerful reducing agent, a method involving high-temperature combustion, and a method involving the removal of particles from the exhaust gas, the addition of hydrogen or water and oxygen, and thermal decomposition above 600° C. Recently, a method for removing PFCs through exposure to a process gas in a plasma state at 10,000 K and rapid cooling has been proposed. However, in such a high-temperature thermal plasma technique, it is necessary to heat the process gas to at least 600° C. and to keep this high temperature level for a period of time, and thus energy consumption is high. Moreover, the throughput and performance are not high when compared with labor and cost inputs.
According to most techniques using low-temperature plasma, similar to the above-described U.S. SIR, PFCs are converted into solid waste particles by the addition of alkaline earth metals or other additives. However, as described above, these techniques are considered to be uneconomical due to the need for collateral equipment, and the accompanying maintenance and management costs.